Periodic Reporting for period 4 - BYONIC (Beyond the Iron Curtain) Reporting period: 2021-12-01 to 2023-05-31 Summary of the context and overall objectives of the project This ERC project, BYONIC, aims to improve our understanding of the cycling of multiple essential resources in the ocean and their impact on phytoplankton productivity. As one of the largest carbon reservoirs on Earth, the ocean is an essential component of the global carbon cycle, with this activity underpinned by the activity of microscopic plants known as phytoplankton who catalyse the transfer of carbon dioxide between the atmosphere and the ocean. The overall activity of phytoplankton is also of importance as it forms the base of pelagic ocean food webs and supports important ecosystem services. Accordingly, we need to understand the drivers of phytoplankton growth and how it will vary in response to environmental change.Our current conceptual model behind our understanding of the impact of environmental variability on phytoplankton growth is very simple and ignores the role of multiple micronutrient resources in shaping spatio-temporal variability. This ERC project will respond to these gaps in two main ways: firstly, by developing representations of multiple micronutrient resources in global ocean biogeochemical models to understand the drivers of their variability and secondly, to assess and constrain how resource variability affects microbial activity in the context of a changing climate. BYONIC will address these questions via three overarching research questions: 1) How do environmental gradients affect cellular trade-offs and the co-limitation of growth? 2) What controls the oceanic distributions of Co, Cu, Mn and Zn? and 3) Does a realistic representation of resource limitation/co-limitation effect the response of ocean ecosystems to environmental change. The project is then designed with five workpackages to respond to these questions. Two are based around developing representations of multiple nutrient ccling and cellular growth co-limitation, and three focus on key science outcomes linked to the three overarching research questions. Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far We have delivered a set of papers concerning the implementation of new models for simulating the biogeochemical cycling of multiple resources and their isotopes (WP2) and used these models to understand the main drivers of change (WP4). We have completed work starting to examine co-limitation of phytoplankton and bacteria and the role of zooplankton in recycling essential resources (WP3)We have developed a new theoretical framework able to represent the interactions between multiple essential resources (WP2) and have begun work to examine the implications for resource limitation/co-limitation in the contemporary ocean (WP3)Climate change simulations are ongoing examining how environmental variations affects the large scale cycling of multiple resources and how resource co-limitation affects microbial activity (WP5) Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far) Our new model, representing the global cycling of eight essential resources has advanced the state of the art for global ocean biogeochemical models. Coupled with our new framework for representing the interactions between essential resources in shaping microbial growth (WP2) will provide new insights into the contemporary patterns of microbial growth in the ocean (WP3) as well as the impact of climate change (WP5). In particular, this is being catalysed by our team driving forward new links between biological oceanographers, microbial ecologists and molecular biologists. In parallel, we are planning to produce results associated with iron isotopes, and their role as a signal of change in the iron cycle. We except in the second half of the project a set of high profile papers on: (i) impact of climate change on cycling of mutiple micronutrients, (ii) how does uncertainty associated with iron uptake affect projections of climate change impacts on NPP?, (iii) a new framework for representing multi-nutrient co-limitation in the global ocean (iv) how do Co-Mn-Zn interact to shape microbial growth? and (v) impact of multi-resource interaction on climate change impacts on NPP b1-schematic-of-scales.png
